Citing a desire to avoid surgery for an ailing back and wanting to spend more time with his family, the two-time Cy Young Award winner retired Monday after 16 seasons in the major leagues with the Toronto Blue Jays and Philadelphia Phillies.

Halladay signed a one-day contract to retire as a member of the Blue Jays, where he spent the first 12 years of his career. The 36-year-old right-hander choked up and held back tears while making the announcement at a news conference at the winter meetings in Lake Buena Vista, Fla.

“As a baseball player, you realize that’s something you can’t do the rest of your life,” Halladay said. “I really don’t have any regrets. You realize there’s other things for you to accomplish in life.”

Halladay pitched a perfect game and also a postseason no-hitter. But never made it to the World Series and leaves without the ring he badly wanted.

The Phillies had already won three straight division championships, the 2008 World Series and 2009 NL championship by the time Halladay arrived in a blockbuster trade the same day Philadelphia sent ace Cliff Lee to Seattle in a separate deal.

The Phillies had the best record in the majors in Halladay’s first two seasons, but lost to San Francisco in the 2010 NLCS and St. Louis Cardinals in the 2011 NL division series. In his final postseason performance, Halladay lost to Chris Carpenter and the Cardinals 1-0 in the decisive Game 5 of that 2011 matchup.

Down 2-1 in the series, the Cardinals won two straight to upset the Phillies after a squirrel scampered across home plate as Skip Schumaker batted against Roy Oswalt.

“I think the one thing I took away from that is you can have the best team on paper, you can have the guys who want it the most,” Halladay said. “But when the squirrel runs across home plate while your team is trying to pitch, there is nothing you can do about that. So you really start to realize there are a lot of things out of your control. It takes more than nine guys. It takes nine guys, and it takes the 25 on the roster. It takes the coaches, the staff, and it takes a lot of luck.”

Halladay played for the Phillies from 2010-13, finishing with two injury-plagued seasons. He won an NL Cy Young Award in 2010, throwing a perfect game that season and a no-hitter in his first postseason appearance.

Halladay was 203-105 with a 3.38 ERA in 416 career games, including 390 starts. He had 67 complete games and 20 shutouts. His resume includes three 20-win seasons, eight All-Star games, and three other top-3 finishes for the Cy Young Award.

Known as a workhorse, Halladay led the league in innings four times and in complete games seven times.

“He was one of the best competitors who ever played this game and taught everyone around him to prepare the right way in order to be the best,” Phillies lefty Cole Hamels said.

Halladay was a six-time All-Star, won the 2003 AL Cy Young Award and went 148-76 with a 3.43 ERA in 12 seasons with the Blue Jays. He was traded to the Phillies after the 2009 season, and was 40-16 with a 2.40 ERA in his first two years in Philadelphia. But back and shoulder issues limited Halladay in 2012-13. He was 15-13 with a 5.15 ERA in 38 starts.

Halladay had shoulder surgery during the season and returned in September, but clearly wasn’t right. He was 4-5 with a 6.82 ERA in 13 starts this year.

“It’s so much fun to play the game and go out and compete,” he said. “I looked forward to that fifth day more than anything. To go out there and know it’s not going to feel good and I wasn’t going to do it the way I wanted was frustrating. I tried to give everything I can but something was holding me back. I felt I couldn’t give them what I wanted to.”

Despite Halladay’s decline, the Phillies were still interested in bringing him back for another year if he was healthy and at a price much lower than the $20 million he earned in each of the last three seasons. He was a popular teammate and a valued presence in the clubhouse for his influence and strong work ethic.

“Roy Halladay is the ultimate competitor,” second baseman Chase Utley said. “He is by far the hardest worker that I’ve ever seen and treated every game as if it were his last. It was no coincidence why he was the best pitcher of his era. I’m honored to have had the opportunity to watch him pitch for four years. I’ll miss his presence and passion but, most of all, I will miss his intensity.”